WO2016083598A1

WO2016083598A1 - Device and method for stimulating slow brain waves

Info

Publication number: WO2016083598A1
Application number: PCT/EP2015/077959
Authority: WO
Inventors: Quentin SOULET DE BRUGIERE; Hugo MERCIER; Mathieu GALTIER
Original assignee: Dreem
Priority date: 2014-11-27
Filing date: 2015-11-27
Publication date: 2016-06-02
Also published as: FR3029117B1; EP3223695A1; US10695528B2; US20170340855A1; FR3029117A1

Abstract

The invention relates to a self-contained device (1) for stimulating slow brain waves, capable of being worn by a person (P), in particular during a period of time when said person is sleeping. The device (1) comprises a supporting element (2), capable of surrounding the head of a person, and on which electrodes (3) are mounted in contact with the person in order to acquire a measurement signal that represents a physiological electrical signal of the person; an acoustic transducer (4) for emitting an acoustic signal (A) stimulating the inner ear of the person; and on-board conditioning and control electronics (5) for, in flexible real time, receiving the measurement signal and controlling the emission of an acoustic signal (A) synchronised with a predefined slow brain wave time pattern.

Description

Device and method for stimulating slow brain waves

FIELD OF THE INVENTION

The invention relates generally to the field of controlling brain activity during sleep and in particular to the stimulation of slow brain waves to enhance the beneficial effects of a person's sleep.

The object of the invention is, firstly, a device for stimulating slow brain waves, and secondly, a method of stimulating the slow brain waves of a person in which the person wears such a device.

BACKGROUND OF THE INVENTION

During a person's sleep period, many crucial biological mechanisms take place, such as the development of immune defenses, cellular regeneration or the consolidation of memory.

Thus, a deficit or a degradation of sleep are today recognized as being sources of memory disorders and important factors of development or aggravation of serious pathologies such as Alzheimer's, Parkinson's, arterial over-tension or obesity.

In particular, it has been observed that these beneficial biological mechanisms associated with sleep are associated with a particular brain activity exhibiting particular frequency waves: slow brain waves.

In modern societies, stress and productivity constraints lead to deterioration and shortening of sleep, including sleep during which the beneficial biological mechanisms mentioned above are implemented. This has adverse impacts in the short term (fatigue, memory, concentration) and in the long term (increased risks of occurrence of chronic diseases).

There is thus a general need to enhance the beneficial effects of a person's sleep, especially when the duration and quality of sleep are subject to strong external constraints.

For this purpose, there are known devices for stimulating the brain, particularly during the phases of deep sleep of a person, who seek to promote the phases of deep sleep.

Thus, for example, the document US8029431 describes a system applying, during a phase of deep sleep, non-invasive stimulations to the brain of a person. The system compiles a central unit receiving the signals measured by an electrode panel to acquire a person's encephalogram and control a transcranial magnetic stimulation device to periodically stimulate the brain of the person when in deep sleep at a preset frequency to improve deep sleep.

Such a device has drawbacks, in fact a transcranial stimulation device is bulky and unsuitable for use in a daily context since it involves the use of an articulated support foot on which is hung a coil powered by a generator . In addition, such a device must be adequately disposed relative to the target brain areas which is difficult to implement throughout a night's sleep, especially when the person moves in bed, and therefore involves appealing has a robotic arm controlled by computer, restricting the applicability of the solution in everyday life. Moreover, a periodic stimulation is not suitable for all people given the variability of brain waves between individuals, the implementation of such a device therefore requires the presence of trained medical personnel to determine and adapt the frequency of stimulation to the user, which further complicates the daily adoption of such a device and its ease of use.

Thus, there is a need for a cerebral slow wave stimulation apparatus which is simple to use, accessible to non-medically trained personnel, which is compact and comfortable so that it can be used in a day-to-day context, which significantly enhances the beneficial effects of a person's sleep, which improves the stability and duration of sleep phases, which is easily adaptable to the user so that it can be used without complex modifications by a variety of people, and which is simple and inexpensive to manufacture to ensure its accessibility to the general public.

OBJECTS OF THE INVENTION

For this purpose, the invention firstly relates to an autonomous device for stimulating slow brain waves adapted to be worn by a person, particularly during a sleep period of said person,

the device comprising a support element, able to surround at least partially a head of a person so as to be maintained, on which are mounted:

a plurality of electrodes adapted to be in contact with the person to acquire at least one measurement signal representative of a physiological electrical signal of said person,

at least one acoustic transducer adapted to emit an acoustic signal stimulating an inner ear of said person, and

an on-board conditioning and control electronics capable, in real time, of receiving the measurement signal of the plurality of electrodes and controlling the transmission by the acoustic transducer of an acoustic signal synchronized with a predefined temporal pattern of cerebral slow wave.

In preferred embodiments of the invention, one or more of the following may also be used:

to control the transmission by the acoustic transducer of an acoustic signal synchronized with a predefined temporal pattern of a slow cerebral wave, the on-board conditioning and control electronics is able to: determine, from the measurement signal, a cerebral slow waveform,

determining, from said cerebral slow wave form, at least one time synchronization time between the predefined cerebral slow wave temporal pattern and a predefined temporal pattern of the acoustic signal, and

controlling the acoustic transducer so that the predefined temporal pattern of the acoustic signal is transmitted at said timing instant of synchronization;

the means for determining, from the measurement signal, a cerebral slow waveform of the on-board conditioning and control electronics comprise a phase-locked loop;

the phase-locked loop is adapted to enslave an instantaneous phase of the temporal form on an instantaneous phase of the measurement signal;

the phase-locked loop comprises means for determining an instantaneous phase difference between the time form and the measurement signal, in particular a low-pass filter applied to a product between the time form and the measurement signal;

the predefined cerebral slow wave temporal pattern comprises a predefined range of instantaneous phase values of the time form and / or a predefined range of absolute magnitude value of the measurement signal;

the acoustic transducer is a loudspeaker stimulating the inner ear of the person by an auditory canal, or an osteophonic device stimulating the person's inner ear by bone conduction;

the on-board conditioning and control electronics receives the measurement signal from the plurality of electrodes and controls the acoustic transducer via wired links;

the device further comprises a memory, mounted on the support element, controlled by the on-board conditioning and control electronics, and capable of storing the measurement signals, preferably a memory capable of storing the measurement signals on a duration of several hours, preferably at least eight hours;

the memory is able to memorize a mean cerebral slow wave frequency of the person;

the device further comprises a communication module with an external server, mounted on the support element, controlled by the on-board conditioning and control electronics, and able to transfer the measured measurement signals to the external server, in particular after a sleep period of said person; the device is autonomous and capable of implementing a cerebral slow wave stimulation operation without communicating with an external server, in particular without communicating with an external server over a period of several minutes, preferably several hours, preferably at least eight hours;

the device comprises a battery mounted on the support element and capable of supplying the plurality of electrodes, the acoustic transducer and the on-board conditioning and control electronics, preferably over a period of several hours without recharging the battery, preferably at least eight hours;

the cerebral slow wave has a frequency lower than 5 Hz and greater than 0.3 Hz;

the acoustic signal is an intermittent signal and a duration of the acoustic signal is less than a period of a cerebral slow wave, preferably less than a few seconds, preferably less than one second;

the acoustic signal is a continuous signal and the duration of the acoustic signal is greater than a period of a slow cerebral wave;

the device comprises a first acoustic transducer and a second acoustic transducer respectively capable of emitting acoustic signals respectively stimulating a right inner ear and a left inner ear of the person, and the acoustic signals emitted by the first and the second acoustic transducer are binaural acoustic signals;

the predefined cerebral slow wave temporal pattern corresponds to a local temporal maximum of a cerebral slow wave, a local temporal minimum of a cerebral slow wave, a rising edge or a falling edge of a cerebral slow wave; maximum or local minimum of a cerebral slow wave, a predefined succession of at least one local temporal maximum and at least a local temporal minimum of a cerebral slow wave or a rising or falling edge of such a succession;

the support element comprises a device for adjusting the diameter of the head of a person making it possible to modify a dimension of said support element as a function of a diameter of the head of a person;

the device for adjusting the support element is a flexible and flexible portion of the support element, in particular a portion of fabric or elastomer;

the device for adjusting the support element comprises at least two parts, rigid or semi-rigid, movable relative to one another;

the support element is able to surround at least one half of a circumference of the head of the person P r

the device has a total weight of less than 200 grams.

The subject of the invention is also a method of stimulating a person's slow brain waves, in particular during a sleep period of said person, in which the person wears a device according to one of claims 1 to 18, the support element of the device at least partially surrounding the head of said person so as to be maintained therein, the method comprising, in real time flexible:

acquiring at least one measurement signal representative of a physiological electrical signal of the person by means of the plurality of electrodes in contact with the skin of the person,

receiving said measurement signal by on-board electronics for conditioning and control, and

the transmission by the acoustic transducer, on command of the on-board conditioning and control electronics, of an acoustic signal synchronized with a predefined temporal pattern of cerebral slow wave.

According to one embodiment, the transmission of an acoustic signal synchronized with a predefined temporal pattern of a slow cerebral wave comprises:

the determination, from the measurement signal, of a cerebral slow waveform,

determining, from said cerebral slow wave form, at least one timing instant of synchronization between the predefined cerebral slow wave pattern and a predefined temporal pattern of the acoustic signal, and

the control of the acoustic transducer so that the predefined temporal pattern of the acoustic signal is emitted at said timing instant of synchronization.

the determination, from the measurement signal, of a cerebral slow wave temporal shape comprises the servocontrol of an instantaneous phase of said temporal form over an instantaneous phase of the measurement signal;

the determination, from the measurement signal, of a cerebral slow wave temporal shape comprises:

determining a temporal shape oscillating at a medium cerebral slow wave frequency of the person,

determining an instantaneous phase difference between said time form and the signal of measured,

servocontrolling an instantaneous phase of said time form on an instantaneous phase of the measurement signal as a function of said instantaneous phase difference;

determining an instantaneous phase difference between said time form and the measurement signal comprises applying a low-pass filter to a product between the time form and the measurement signal;

the predefined temporal pattern of cerebral slow wave has a predefined range of instantaneous phase values of the temporal form and / or a predefined range of absolute value of amplitude of the measurement signal;

the timing instant of synchronization is determined as being a time instant during which the instantaneous phase of the time form belongs to said predefined range of instantaneous phase values of the time form if and only if the absolute value of amplitude of the signal of measurement previously belonged to said predefined range of absolute value of amplitude of the measurement signal;

a first time instant II is determined during which the absolute value of amplitude of the measurement signal S belongs to the predefined range of absolute value of amplitude of the measurement signal,

a second temporal instant 12, after the first time instant II, is determined, during which the instantaneous phase of the temporal form F belongs to the predefined range of instantaneous phase value of the temporal form F, and

if the first time instant II and the second time instant 12 are separated by a duration less than a predefined maximum duration, the synchronization time instant I is defined as the second time instant 12;

determining the average cerebral slow wave frequency of the person from a measurement signal acquired during a sleep period of said person preceding the sleep period during which the method is implemented;

the dynamically determined mean cerebral slow wave frequency of the person,

in particular, the average cerebral slow wave frequency of the person is determined dynamically from a portion of the measurement signal acquired over a predefined time period preceding the instant at which the average frequency determination operation is implemented. cerebral slow wave of the person;

the predefined temporal pattern M2 of the acoustic signal comprises a predefined number of intermittent signals, in particular less than five intermittent signals.

According to one embodiment, the transmission by the acoustic transducer, on command of the on-board conditioning and control electronics, of an acoustic signal synchronized with a predefined temporal pattern of slow cerebral wave is repeated at least once, in particular at less once during a sleep period of the person.

With these provisions, the invention can provide a device and a method for stimulating slow brain waves that is simple to use, accessible to non-medically trained personnel, which is compact and comfortable so that it can be used in a context of daily life, which reinforces the beneficial effects of a person's sleep, which improves the stability and duration of sleep phases, which is easily adaptable to the user in order to be able to be used without complex modifications by a variety of people, and which is simple and inexpensive to manufacture to ensure its accessibility to the general public

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention will become apparent from the following description of several of its embodiments, given by way of non-limiting examples, with reference to the accompanying drawings.

On the drawings:

FIG. 1 is a schematic view of an autonomous device for stimulating slow brain waves carried on the head of a person according to one embodiment of the invention,

FIG. 2 is a detailed perspective view of an autonomous device for stimulating slow brain waves according to an embodiment of the invention in which the device comprises in particular a first and a second acoustic transducer respectively capable of transmitting signals. stimulating respectively a right inner ear and a left inner ear of the person,

FIG. 3 is a block diagram of the device of FIG. 2 illustrating the elements of the device and the functional links between these elements,

FIG. 4 is a flowchart illustrating an embodiment of a method for stimulating slow brain waves according to an embodiment of FIG. The invention,

FIG. 5 illustrates a cerebral slow wave temporal shape, an acoustic signal and predefined temporal patterns according to an exemplary embodiment of the invention.

In the different figures, the same references designate identical or similar elements.

DESCRIPTION DETAILED

Referring firstly to Figures 1 and 2, the invention firstly relates to a device 1 for stimulating slow brain waves.

The device 1 is adapted to be worn by a person P, especially during a sleep period of the person.

The device is particularly adapted to be worn on the head of the person P.

For this purpose, the device 1 comprises a support element 2. The support element 2 is able to surround at least partially the head of the person P so as to be maintained there. In one embodiment of the invention illustrated in FIG. 1, the support element 2 is in particular able to surround at least a portion of a circumference of the head of the person P, in particular to surround at least one half of a circumference of the head of the person P, or completely surround a diameter of the head of the person P.

In the embodiment illustrated in FIG. 1, the support element 2 comprises several branches 2a, 2b, 2c, 2d. The support element comprises in particular four branches connected to each other at the location of branches connecting points 2e, 2f. The branches 2a, 2b, 2c, 2d surround different portions of the head of the person P so as to ensure a stable support and a location precise device 1 on the person P.

Thus for example a first branch 2a surrounds a rear of the head, a second branch 2b surrounds a top of the head. The first and second branches 2a, 2b are respectively connected at their respective ends at a connecting point of left lateral branches 2e and a connecting point of right lateral branches 2f respectively located near the left and right temples. of the person P. Finally, the third and fourth branches 2c, 2d respectively extend from the connection points of left lateral branches 2e and right lateral 2f, towards the front of the person P.

The device 1 furthermore comprises a plurality of electrodes 3, at least one acoustic transducer 4 and an on-board electronics 5 for conditioning and control.

The electrodes 3, acoustic transducer 4 and electronics 5 are operably connected to each other. Thus, the on-board electronic conditioning and control electronics 5 is in particular able to control, and receive information from, the plurality of electrodes 3, and is also able to control and control the emission by the acoustic transducer 4 of a acoustic signal A.

For this purpose, the electrodes 3, the acoustic transducer 4 and the electronics 5 are mounted on the support element 2. In this way, the electrodes 3, the acoustic transducer 4 and the electronics 5 are close to each other if although the communication between these elements 3, 4, 5 is particularly fast and at high speed. In the example of FIG. 1, the electrodes are in particular mounted on the third and fourth branches 2c, 2d, the electronics 5 is mounted on the first branch 2a, and two acoustic transducers 4 are mounted respectively close to the connection points of left lateral branches 2e and right lateral 2f. Other arrangements of the components of the device 1 are of course conceivable.

This makes it possible to implement in real time a flexible stimulation operation of the slow brain waves of a person P.

Thus, in particular, the electronics 5 are able, in real time, to receive a measurement signal S of the plurality of electrodes 3 and to control the emission by the acoustic transducer of an acoustic signal A synchronized with a predefined temporal pattern T of a slow cerebral wave of the person P.

By "synchronized with a predefined temporal pattern of a cerebral slow wave" is meant in particular that the acoustic signal emitted by the device is synchronized in time with a cerebral slow wave of the person. More specifically, it is understood that the acoustic signal emitted by the device is synchronized in time with an instantaneous phase of a cerebral slow wave of the person as detailed below.

By "soft real time" is meant an implementation of the stimulation operation such as temporal constraints on this operation, in particular on the duration or repetition frequency of this operation. , are respected on average over a predefined total implementation period, for example a few hours. In particular, the implementation of said operation may at times exceed said temporal constraints as long as the average operation of the device 1 and the average implementation of the method respects them over the total duration of implementation. predefined implementation. In particular, time limits may be predefined beyond which the implementation of the stimulation operation must be stopped or paused.

To allow such a flexible implementation in real time, a maximum distance between the electrodes 3, the acoustic transducer 4 and the electronics 5 may be less than about one meter and preferably less than a few tens of centimeters. In this way, a sufficiently fast communication between the elements of the device 1 can be guaranteed.

The electrodes 3, the acoustic transducer 4 and the electronics 5 can for example be housed in the cavities of the support element 2, clipped onto the support element 2 or else fixed to the support element 2, for example by gluing, screwing or any other suitable fastening means. In one embodiment of the invention, the electrodes 3, the acoustic transducer 4 and the electronics 5 can be mounted on the support member 2 removably.

Referring now also to FIG. 3, in an advantageous embodiment of the invention, the on-board conditioning and control electronics 5 are functionally connected to the electrodes 3 and to the acoustic transducer 4 via wired links. 10. In this way, the exposure of the person P to electromagnetic radiation is reduced.

The acoustic transducer 4 is able to emit an acoustic signal A stimulating at least one inner ear of the person P.

In a first embodiment illustrated in particular in FIGS. 1 and 2, the transducer Acoustic 4 is an osteophonic device stimulating the inner ear of the person P by bone conduction.

This osteophonic device 4 may for example be able to be placed close to the ear, for example above as illustrated in FIG. 1, in particular on a skin zone covering a cranial bone.

In a second embodiment, the acoustic transducer 4 is a loudspeaker stimulating the inner ear of the person P by an auditory canal leading to said inner ear.

This speaker may be disposed outside the ear of the person P or in the ear canal.

The acoustic signal A is a modulated signal belonging at least partially to a frequency range audible by a person P, for example the range from 20 Hz to 30 kHz.

The electrodes 3 are able to be in contact with the person P, and especially with the skin of the person P to acquire at least one measurement signal S representative of a physiological electrical signal E of the person P.

The physiological electrical signal E may especially comprise an electroencephalogram (EEG), an electromyogram (EMG), an electrooculogram (EOG), an electrocardiogram (ECG) or any other biosignal measurable on the person P.

In particular, the physiological electrical signal E comprises advantageously an electroencephalogram (EEG) of the person P.

To this end, in one embodiment of the invention, the device 1 comprises at least two electrodes 3 including at least one reference electrode 3a and at least one EEG measuring electrode 3b. The device 1 may further comprise a ground electrode 3c.

In a particular embodiment, the device 1 comprises at least three EEG measuring electrodes 3c, so as to acquire physiological electrical signals E comprising at least three electroencephalogram measurement channels.

The EEG measuring electrodes 3c are for example disposed on the surface of the scalp of the person P.

In other embodiments, the device 1 may further comprise an electrode for measuring the EMG and, optionally, an electrode for measuring EOG.

The measurement electrodes 3 may be reusable electrodes or disposable electrodes. Advantageously, the measurement electrodes 3 are reusable electrodes so as to simplify the daily use of the device.

The measurement electrodes 3 may be, in particular, dry electrodes or electrodes covered with a contact gel. The electrodes 3 may also be textile or silicone electrodes.

In one embodiment of the invention, the measurement electrodes 3 are active electrodes able to perform a pretreatment of the measurement signal S, for example at least one of the following pretreatments:

a frequency filtering, for example a frequency filtering of the measurement signal S in a range of temporal frequencies of interest, for example a frequency range comprised in a range from 0.3 Hz to 100 Hz,

an amplification, for example an amplification of the measurement signal S by a factor ranging from 10 ^Λ 3 to 10 ^Λ 6, and / or a sampling of the measurement signal S by means of an analog-digital converter able, for example, to sample the measurement signal S with a sampling rate of a few hundred Hertz, for example 256 Hz or 512 Hz.

Such pretreatment of the measurement signal S may for example be implemented by an analog module of the measuring electrode 3 or by an analog module disposed in proximity to the measuring electrode 3.

The on-board electronic conditioning and control electronics 5 receives the measurement signals S from the electrodes 3, possibly pre-processed as detailed above.

If the measurement signals S received by the electronics 5 are not pretreated, the electronics 5 may in particular implement one and / or the other of the pretreatments detailed above.

The on-board electronic packaging electronics 5 comprises one or more electronic chips, for example at least one microprocessor.

As detailed above, the on-board electronic conditioning and control electronics 5 is able to implement a stimulation operation of the slow brain waves of the person P, an operation which will now be described in more detail.

By "cerebral slow wave" is meant in particular a cerebral electrical wave of the person P having a frequency of less than 5 Hz and greater than 0.3 Hz. By "cerebral slow wave", it is possible to hear a cerebral electrical wave of the person P having a peak to peak amplitude of, for example, between 10 and 200 microvolts.

In addition to the very low frequency waves below 1 Hz, we also mean by slow wave particularly delta waves of higher frequencies (usually between 1.6 and 4 Hz). A cerebral slow wave can still be understood to mean any type of wave having the characteristics of frequency and amplitude mentioned above. Thus, for example, phase 2 sleep waves called "K-complexes" can be considered as slow brain waves for the invention.

It is thus understood that the implementation of the cerebral slow wave stimulation operation according to the invention may not be limited to a deep sleep phase of the person P (commonly called stage 3 or stage 4) but may also be performed during other phases of sleep, for example during the light sleep of the person (usually called stage 2).

It should be noted, however, that such slow brain waves are not usually observed in the phases of paradoxical sleep, that is to say in particular the phases of dreams.

In general, the implementation of the invention may not be limited to a particular sleep phase of the person P (as identified for example in the AASM standards, acronym for "American Academy of Sleep Medicine").

To implement the stimulation operation of the slow brain waves, the electronics 5 is for example able, from the measurement signal S, to first determine a temporal shape F of a cerebral slow wave C such that illustrated in Figure 5.

In a first embodiment, the time form F is a series of sampled points of amplitude values of the measurement signal S, possibly pre-processed as mentioned above, said series of measuring points possibly being interpolated or resampled.

In a second embodiment, the time form F is a series of amplitude values generated by a phase locked loop, or PLL, (commonly referred to as PLL, acronym for the English term "Phase locked loop"). The phase-locked loop is such that the instantaneous phase of the temporal form F at the output of said loop is slaved to the instantaneous phase of the measurement signal S.

The phase-locked loop may be implemented by analog means or digital means, for example within a programmable digital electronic chip or an analog electronic component.

As detailed below, said phase-locked loop may comprise means for determining an instantaneous phase difference between the time form F and the measurement signal S. Said means can also be implemented by analog means or digital means, for example within a programmable digital electronic chip or an analog electronic component.

In one embodiment of the invention, the temporal form F can therefore be determined by a phase-locked loop (also called a phase-locked loop).

The phase locked loop may be such that the instantaneous phase of the time form F is slaved to the instantaneous phase of the measurement signal S.

A mean c slow brain wave frequency of the person P can be determined by a brain wave analysis of the person P.

In a first embodiment, it is possible determining the average c slow brainwave frequency of the person P during a prior stage of P-wave analysis.

The prior step of analyzing the brain waves of the person P may for example comprise the analysis of the measurement signal S acquired during a previous sleep period to determine an average frequency of the slow brain waves of the person P.

In order to determine the average frequency of the slow brain waves, the measuring signal S acquired during a preceding sleep period can be filtered frequently or temporally, in particular to keep only the measurement signal associated with a sleep period of interest, for example a period of deep sleep, and / or to remove measurement artifacts or too high frequencies.

Then, an average frequency of cerebral slow waves can be extracted from said filtered measurement signal.

In a second embodiment, it is possible to dynamically determine the mean c slow brainwave frequency of the person P during the implementation of the method.

For this purpose, it is possible to analyze a portion of the measurement signal S acquired over a predefined temporal duration preceding the instant at which the operation of determining the average cerebral slow wave frequency of the person is implemented. The measurement signal S can for example be stored in a buffer memory for this purpose.

Such a predefined temporal duration can for example go from a few tens of seconds to a few minutes.

Prior to said analysis it is also possible to implement filtering operations of said portion of the measurement signal as detailed above.

Analysis of said portion of the measurement signal S makes it possible to extract a mean frequency of cerebral slow waves from said measurement signal portion.

Once the c-wave average wavelength of the person P has been determined, a temporal form F can be generated at said mean wavelength of the cerebral slow wave.

The measurement signal S, possibly previously filtered, can be normalized, for example between -1 and 1.

An instantaneous phase difference D between the time form F and the measurement signal S can then be determined, for example as follows.

Assuming that the measurement signal S and the time form F have the following simplified forms:

S = cos (wt + φ) (1)

F = cos (wt + ψ) (2)

where φ is an instantaneous phase of the measurement signal S, ψ is an instantaneous phase of the temporal form F and w is the average cerebral wave frequency C.

An instantaneous phase difference D between the time form F and the measurement signal S can then be determined as:

D = LP [cos wt + φ) cos wt + ψ)] sin φ- ψ ^ φ- ψ (3) where LP is a low-pass function.

It is then possible to control the temporal form F as a function of the instantaneous phase difference D to synchronize the instantaneous phase of the temporal form F and the instantaneous phase of the measurement signal S.

Thus, in the example of equations (1) to (3) given above, it will be sought to minimize the instantaneous phase difference D to synchronize the time form F and the measurement signal S.

For this, the temporal form F can be shifted temporally or shifted in phase, for example by directly adjusting the instantaneous phase ψ of the temporal form F, so as to minimize the phase signal. The information on the amplitude, absolute or relative, of the measurement signal S can be reassociated with the temporal form F so as to obtain a representation of the instantaneous phase and the amplitude of the measurement signal.

In general, therefore, it is understood that the temporal form F is a representation of the brain wave C which can directly correspond to the measurement signal S and / or can be obtained by a phase-locked loop on the basis of the measurement signal S.

Generating the temporal shape F by a phase-locked loop notably makes it possible to obtain a cleaner signal.

In particular, the instantaneous phase of the temporal form F and the cerebral wave C are synchronized temporally.

In the present description, therefore, the term "brain wave C" is used to mean the values taken by the temporal form F.

From this temporal form F, the electronics 5 is able to determine at least a temporal time I of synchronization between a predefined temporal pattern Ml of cerebral slow wave C and a predefined temporal pattern M2 of the acoustic signal A.

Then, the electronics 5 is able to control the acoustic transducer 4 so that the predefined temporal pattern M2 of the acoustic signal A is emitted at the timing instant I of synchronization. The predefined temporal pattern Ml of cerebral slow wave C is therefore a pattern of amplitude and / or phase values of the temporal form F which represents the cerebral slow wave C and / or the measurement signal S.

By amplitude and / or phase value pattern is meant a temporal succession of amplitude and / or phase values, associated where appropriate with predefined time-points (ie a value curve). amplitude and / or phase). It is also understood, more simply an amplitude and / or phase value or an amplitude and / or phase value range.

The timing instant of synchronization I can thus be determined when the amplitude and / or the phase of the temporal form F which represents the cerebral slow wave C and / or of the measurement signal S are equal to the amplitude values and / or phase of the predefined temporal pattern Ml.

In particular, the predefined temporal pattern M1 may be a succession of phase values of the temporal form F and may therefore be in particular independent of the absolute value of the amplitude of the time form F.

Thus, for example, the predefined temporal pattern M1 may be a predefined range of instantaneous phase values of the temporal form F.

Such a predefined range of instantaneous phase values of the temporal form F will be for example an instantaneous phase ψ between pi and 3/2 * pi radians, corresponding to a rising edge of the brain wave C for the temporal form F of the Equation (2) indicated above (F = cos (w +) The predefined temporal pattern M1 may also be a succession of relative values of the amplitude of the time form F. Said relative values are for example relative to a maximum amplitude of the predefined or stored time form F. In one embodiment of the invention, the predefined temporal pattern M1 may thus for example correspond to a local temporal maximum of the cerebral slow wave C, a local temporal minimum of the cerebral slow wave C or else a predefined succession of c at least one local temporal maximum and at least one local temporal minimum of the cerebral slow wave C. The predefined temporal pattern M1 may also correspond to a portion of such a maximum, minimum or of such a succession, for example a rising edge, a falling edge or a plateau.

The predefined temporal pattern M1 may also be a function of absolute values of the amplitude of the temporal form F, for example a range of absolute amplitude values of the temporal form F, especially when the temporal form F retains the information on the time domain F. amplitude of the measurement signal S.

By way of non-limiting example, the predefined temporal pattern M 1 may correspond to absolute values of amplitude of the temporal form F less than a predefined trigger threshold of the stimulation, for example absolute values of amplitude less than -30. milliVolts (in this case it is an open range).

The predefined time pattern M1 can comprise several of the different variants described above.

When the predefined time pattern M1 comprises several ranges of values, the timing instant of synchronization I can be determined when said ranges of values are verified simultaneously or successively.

Thus, for example, the predefined temporal pattern M1 may comprise a predefined range of instantaneous phase value of the temporal form F and a range predefined amplitude absolute value of the measurement signal contained in the time form F.

The predefined range of instantaneous phase value is for example the instantaneous phases comprised between pi and 3/2 * pi radians.

The predefined range of amplitude absolute value is, for example, absolute values of amplitude less than -30 milliVolts.

In a first embodiment, the timing instant of synchronization I can be determined as being a time during which the values of the time form F simultaneously check said ranges of instantaneous phase and amplitude absolute value values.

In a second embodiment, the synchronization time instant I can be determined as being a time instant during which the instantaneous phase of the temporal form F belongs to the predefined range of instantaneous phase value of the temporal form F if and only if, previously, the absolute value of amplitude of the measurement signal S has belonged to the predefined range of absolute value of amplitude of the measurement signal.

A maximum time separating the respective memberships of said instantaneous phase and amplitude absolute value audited ranges of respective values can be predefined, in particular to limit false detections of patterns.

More precisely, the absolute amplitude value of the measurement signal S can belong to the predefined range of absolute amplitude value of the measurement signal at a first time instant II. The instantaneous phase of the temporal form F can belong to the predefined range of instantaneous phase value of the temporal form F at a second temporal instant 12, after the first instant temporal I 1.

If the first and the second time instant II and 12 are separated by a duration less than the said predetermined maximum duration, the synchronization time instant I can then be defined as the second time instant 12.

In the same manner, the predefined temporal pattern M2 of the acoustic signal may be a pattern of amplitude and / or phase values of the acoustic signal A.

In a first embodiment, the acoustic signal is for example an intermittent signal as illustrated in FIG. 5. This intermittent signal is for example emitted for a duration less than a period of a slow cerebral wave. The duration of the intermittent signal is for example less than a few seconds, preferably less than one second. In an example given for purely indicative and non-limiting, the acoustic signal A is for example a type 1 / f pink noise pulse with a time duration of 50 to 100 milliseconds with a rise and fall time of a few milliseconds. Still in a nonlimiting manner and to fix the ideas, in this example, the predefined temporal pattern Ml of cerebral slow wave C can for example correspond to a rising edge of a local maximum of the cerebral slow wave C. The temporal motif predefined M2 of the acoustic signal A can then be for example a rising edge of the pink noise pulse. In this example, the timing instant I of synchronization between the predefined temporal pattern Ml of cerebral slow wave C and the predefined temporal pattern M2 of the acoustic signal A can for example be defined so that the rising edge of the pink noise pulse A and the rising edge of the local maximum of the cerebral slow wave C are synchronized, that is, to say concomitant.

The predefined temporal pattern M2 of the acoustic signal may comprise a predefined number of intermittent signals, in particular less than five intermittent signals, for example 2 or 3 pink noise pulses.

In another embodiment, the acoustic signal A may be a continuous signal. The duration of the acoustic signal A may then in particular be greater than a period of the cerebral slow wave C. By "continuous signal" is meant in particular a signal of great duration in front of a period of the cerebral slow wave C.

In this embodiment, the acoustic signal A may be modulated temporally in amplitude, frequency or phase and the predefined temporal pattern M2 of the acoustic signal A may then be such a temporal modulation.

Alternatively, the continuous acoustic signal A may not be modulated temporally, for example in a manner that will now be described.

The device 1 may comprise at least two acoustic transducers 4, in particular a first acoustic transducer 4a and a second acoustic transducer 4b as illustrated in FIG. 2. The first acoustic transducer 4a is able to emit an acoustic signal A1 stimulating a right inner ear of the person P. The second acoustic transducer 4b is able to emit an acoustic signal A2 stimulating a left inner ear of the person P.

In particular, the first and the second acoustic transducers 4a, 4b can be controlled in such a way that the acoustic signals A1 and A2 are binaural acoustic signals A. For this purpose, the signals For example, the acoustic signals A1 and A2 may be continuous signals of different frequencies.

Such acoustic signals A1, A2 are known to generate intermittent pulses in the brain of the person P, in particular called binaural beats.

Still in a nonlimiting manner and to fix the ideas, in this example, the predefined temporal pattern M1 of cerebral slow wave C may, for example, again correspond to a rising edge of a local maximum of the cerebral slow wave C The predefined temporal patterns M2 of the acoustic signals A1, A2 can moreover be ranges of the acoustic signals A1, A2 corresponding temporally to said intermittent pulses generated in the brain of the person P. In this example, the time instant I of synchronization between the predefined temporal pattern M1 of cerebral slow wave C and the predefined temporal patterns M2 of the acoustic signals A1, A2 may for example be defined so that an intermittent pulse generated in the brain of the person P is synchronized temporally with the rising edge of the local maximum of the cerebral slow wave C.

According to the embodiments and according to the selected time pattern Ml, different embodiments can be envisaged for determining the time instant I of synchronization.

FIG. 5 illustrates an example of predefined temporal patterns M1 and M2.

Furthermore, in order to determine the time instant I, the electronics 5 can for example compare the amplitude values of the measurement signal S, possibly filtered and / or normalized, with an amplitude threshold.

In the example given above for purely non-limiting reasons, the predefined temporal pattern Ml of slow wave C corresponds to a rising edge of a local maximum of the cerebral slow wave C. A temporal instant I then corresponds to a time instant of exceeding the amplitude threshold, or to a predefined duration immediately following such an overtaking time . The electronics 5 can thus control the acoustic transducer 4 so that the predefined temporal pattern M2 of the acoustic signal A is synchronized temporally with said time instant I.

It is understood that the speed of communication between the electrodes 3, the acoustic transducer 4 and the electronics 5 ensures reliable synchronization and optimal implementation of the stimulation operation.

In an embodiment in which the time form F is a series of amplitude values generated by a phase locked loop, it is possible to determine said time instant I from said phase locked loop, by threshold detection or by predicting future values of time form F.

In this embodiment, the temporal form F may in particular be less noisy than the measurement signal S and allow a facilitated determination of the time instant I of synchronization. In this way, it is thus easier to use the phase values of the temporal form F to identify the time instant I.

In all the embodiments, it is possible to implement a reinforcement learning operation to refine the parameters for determining the time instant I, for example the amplitude thresholds, the shape of the predefined temporal pattern M1 or the parameters of the phase locked loop. Such a reinforcement learning operation is particularly indicated in the measurement of physiological electrical signals which are highly variable from one person to another.

The parameters of the stimulation operation, and in particular the sub-operation for determining the time instant I, can thus be adjusted during the implementation of the stimulation operation or during the implementation. successive stimulation operations, for example to adjust said parameters to the person P.

As has been detailed above, the on-board electronic conditioning and control electronics 5 comprises means for determining a temporal waveform F of a cerebral slow wave, determining at least one timing instant of synchronization I between the predefined temporal pattern of cerebral slow wave (Ml), and control the acoustic transducer 4.

Said means of the on-board electronic packaging and control electronics are, for example, electronic chips, microprocessors and / or electronic memories, possibly mounted and connected together on flexible or rigid printed circuits and connected to each other. the electrodes 3 and the acoustic transducer 4 via the wire links 10.

Moreover, the device 1 may also comprise a memory 6 as illustrated in FIG. 3. The memory 6 is able to be mounted on the support element 2, for example in the manner described above for the electrodes 3, the transducer 4 and the electronics 5. The memory 6 can be permanently mounted on the support element 1 or can be a removable module, for example a memory card such as an SD card (acronym for the term "Secure" Digital "). The memory 6 is in particular functionally connected to the electronics 5. The memory 6 can be controlled by the on-board electronic conditioning and control electronics 5 so as to store the measurement signals S.

In an advantageous embodiment of the invention, the memory 6 is able to store the measurement signals S over a period of several hours, for example at least eight hours so as to cover an average sleep period of a person P .

The device 1 may furthermore comprise a communication module 7 with an external server 100. The communication module 7 may be mounted on the support element 1 in the manner described above for the electrodes 3, the acoustic transducer 4 and the 5. The communication module 7 can be controlled by the on-board electronics 5 conditioning and control.

The electronics 5 may in particular be able to control the communication module 7 to transfer the measurement signals S stored in the memory 6, to the external server 100. This transfer operation can in particular be implemented after a sleep period of the person P.

The communication module 7 may advantageously be a wireless communication module, for example a module implementing a protocol such as Bluetooth or Wi-Fi.

In this way, when the person P is in a sleep period, it is not hampered by cables, especially if it is necessary to perform data transmissions during the sleep period.

The device 1 can also include a battery 8. The battery 8 can be mounted on the element support 1 in the manner described above for the electrodes 3, the acoustic transducer 4 and the electronics 5. The battery 8 may in particular be able to supply the plurality of electrodes 3, the acoustic transducer 4 and the electronics 5, as well as, if necessary, the memory 6 and the communication module 7. The battery 8 is preferably able to provide energy over a period of several hours without recharging, preferably at least eight hours so as to cover a period average sleep of a person P.

In this way, the device 1 can operate autonomously during a sleep period of the person P. In this way in particular, the device 1 is autonomous and able to implement one or more cerebral slow wave stimulation operations without communicate with an external server 100, in particular without communicating with an external server 100 over a period of several minutes, preferably several hours, preferably at least eight hours. This reduces the exposure of the person P to electromagnetic radiation.

By "autonomous" is thus meant that the device can operate for an extended period of several minutes, preferably several hours, especially at least eight hours, without needing to be recharged with electrical energy, to communicate with elements external such as an external server or to be structurally connected to an external device such as a fastener such as an arm or a bracket.

In this way the device is able to be used in the daily life of a person P without imposing particular constraints.

Furthermore, the support element 2 comprises advantageously an adjustment device 9 to the diameter of the head of the person P. This allows an adjustment of the device 1 to the person P and therefore including a good contact of the electrodes 3 with the skin of the person P.

The adjustment device 9 makes it possible to modify a dimension of the support element 2 as a function of a diameter of the head of a person P to adjust it finely to said diameter. In an embodiment illustrated in particular in Figure 1, the adjustment device 9 comprises at least two parts 9a, 9b movable relative to each other. The parts 9a, 9b can be rigid or semi-rigid. In the example of FIG. 1, the parts 9a and 9b are in particular respectively the ends of the third and fourth branches 2c, 2d of the support element 2. In this embodiment, the support element 2 and the parts 9a and 9b have sufficient rigidity for the parts 9a and 9b tend to get closer. In this way, the device 1 can adapt and stay on the head of the person P.

In a variant of this embodiment, the adjustment device 9 may also include a lock 9c able to block or allow relative movement of said two parts 9a, 9b. The latch 9c may be integral with one of the parts 9a, 9b or may be an independent element of the two parts 9a, 9b.

In another embodiment of the invention, the adjustment device 9 is a flexible and flexible portion of the support member 2. This portion may in particular be a portion of fabric or elastomer, for example elastic fabric.

Advantageously, the device 1 can be adapted to be worn effortlessly by the person P for a period of several hours. For this it may in particular have a reduced weight, for example a total weight of less than 200 grams.

With reference to FIG. 4, the subject of the invention is also a method for stimulating the slow brain waves of a person P. This method is particularly suitable for being implemented during a sleep period of the person P.

In this method, the person P carries a device

1 as described above. The support member 2 of the device 1 at least partially surrounds the head of the person P so as to be maintained there. The electrodes 3 are thus in contact with the skin of the person P, so as to be able to pick up physiological electrical signals from the person P. The electrodes 3 are for example arranged in proximity to the brain of the person P to enable the measurement to be made. an encephalogram of the person P.

The method then comprises a cerebral slow wave stimulation operation comprising in particular the following suboperations:

the acquisition of at least one measurement signal S representative of a physiological electrical signal of the person P by means of the plurality of electrodes 3 in contact with the skin of the person P,

the reception of said measurement signal S by the on-board electronic packaging and control electronics, and

the transmission by the acoustic transducer 4, on command of the on-board electronic conditioning and control electronics, of an acoustic signal A synchronized with a predefined temporal pattern Ml of a slow cerebral wave These sub-operations are implemented in real time flexible in the manner detailed above.

Thus, in particular, the emission of an acoustic signal A synchronized with the predefined temporal pattern Ml of a cerebral slow wave comprises:

the determination, from the measurement signal S, of a temporal form F of a slow cerebral wave,

o determining, from said cerebral slow waveform temporal form F, at least one temporal time I of synchronization between the predefined temporal pattern Ml of cerebral slow wave and a predefined temporal pattern M2 of the acoustic signal A, and

the control of the acoustic transducer 4 so that the predefined temporal pattern M2 of the acoustic signal A is emitted at said synchronization time instant I.

In an advantageous embodiment of the invention, the sub-operation of emission by the acoustic transducer 4, on command of the electronics 5, of an acoustic signal A synchronized with the predefined temporal pattern Ml of the slow wave C is reiterated at least once. This sub-operation can in particular be repeated several times during a sleep period of the person.

In an exemplary embodiment, the entire operation of stimulation of the slow brain waves is repeated at least once, and advantageously several times, especially during a sleep period of the person P.

Claims

1. Device (1) autonomous stimulation of slow brain waves adapted to be worn by a person (P), especially during a sleep period of said person,

the device (1) comprising a support element (2) adapted to surround at least partially a head of a person so as to be held thereon, on which are mounted:

a plurality of electrodes (3) adapted to be in contact with the person to acquire at least one measurement signal (S) representative of a physiological electrical signal of said person,

at least one acoustic transducer (4) capable of emitting an acoustic signal (A) stimulating an inner ear of said person, and

an on-board conditioning and control electronics (5) able, in real time, to receive the measurement signal (S) from the plurality of electrodes (3) and to control the transmission by the acoustic transducer (4) an acoustic signal (A) synchronized with a predefined temporal pattern of cerebral slow wave (Ml).

2. Device according to claim 1, wherein for controlling the emission by the acoustic transducer (4) of an acoustic signal (A) synchronized with a predefined temporal pattern of cerebral slow wave (Ml), the electronics (5) ) embedded conditioning and control comprises means of:

o determining, from the measurement signal (S), a temporal form (F) of cerebral slow wave,

o determine, from said time form (F) cerebral slow wave, at least one timing instant of synchronization (I) between the predefined temporal pattern of cerebral slow wave (Ml) and a predefined temporal pattern of the acoustic signal (M2), and

controlling the acoustic transducer (4) so that the predefined temporal pattern of the acoustic signal (M2) is emitted at said timing instant of synchronization (I).

3. The device according to claim 2, wherein the means for determining, from the measurement signal (S), a slow waveform (F) of the cerebral slow wave of the onboard electronic conditioning and control electronics (5). include a phase locked loop.

4. Device according to claim 3, wherein the phase locked loop is adapted to slave an instantaneous phase of the time form (F) on an instantaneous phase of the measurement signal (S).

5. Device according to any one of claims 3 and 4, wherein the phase-locked loop comprises means for determining an instantaneous phase difference (D) between the time form (F) and the measurement signal (S). , in particular a low-pass filter applied to a product between the time form (F) and the measurement signal (S).

6. Device according to any one of claims 1 to 5, wherein the predefined temporal pattern of cerebral slow wave (Ml) comprises a predefined range of instantaneous phase values of the temporal form (F) and / or a predefined range amplitude absolute value of the measurement signal (S).

7. Device according to any one of claims 1 to 6, wherein the acoustic transducer (4) is a loudspeaker stimulating the inner ear of the person by an ear canal, or osteophonic device stimulating the inner ear of the person by bone conduction.

8. Device according to any one of claims 1 to 7, comprising wired links (10) and wherein the electronics (5) embedded conditioning and control receives the measurement signal (S) of the plurality of electrodes. (3) and controls the acoustic transducer (4) via the wire links (10).

9. Device according to any one of claims 1 to 8, further comprising a memory (6), mounted on the support member (2), controlled by the electronics (5) embedded conditioning and control, and suitable storing the measurement signals (S), preferably a memory capable of storing the measurement signals over a period of several hours, preferably at least eight hours.

10. Device according to claim 9, wherein the memory (6) is adapted to memorize a mean w wavelength of cerebral slow wave of the person (P).

11. Device according to any one of claims 9 and 10, further comprising a communication module (7) with an external server (100), mounted on the support member (2) controlled by the electronics (5). embedded conditioning and control, and able to transfer the measurement signals (S) stored in the external server (100), especially after a sleep period of said person.

12. Device according to any one of claims 1 to 11, wherein the device (1) is autonomous and able to implement a cerebral slow wave stimulation operation without communicating with an external server (100), including without communicating. with an external server over a period of several minutes, preferably several hours, preferably at least eight hours.

13. Device according to any one of claims 1 to 12, comprising a battery (8) mounted on the support member (2) and adapted to supply the plurality of electrodes (3), the acoustic transducer (4) and the electronics (5) embedded conditioning and control, preferably over a period of several hours without recharging the battery, preferably i at least eight hours.

14. Device according to any one of claims 1 to 13, wherein the cerebral slow wave has a frequency less than 5 Hz and greater than 0.3 Hz.

15. Device according to any one of claims 1 to 14, wherein the acoustic signal (A) is an intermittent signal and wherein a duration of the acoustic signal is less than a period of a cerebral slow wave, preferably less than a few seconds, preferably less than one second.

Apparatus according to any one of claims 1 to 15, wherein the acoustic signal (A) is a continuous signal and wherein a duration of the acoustic signal is greater than a period of a cerebral slow wave.

17. Device according to claim 16, comprising a first acoustic transducer (4a) and a second acoustic transducer (4b) respectively able to emit acoustic signals (A) respectively stimulating a right inner ear and a left inner ear of the person, and wherein the acoustic signals emitted by the first and second acoustic transducers are binaural acoustic signals.

18. Device according to any one of claims 1 to 17, wherein the predefined temporal pattern of cerebral slow wave (Ml) corresponds to a local temporal maximum of a cerebral slow wave, a local temporal minimum of a slow wave. cerebral, a rising or falling edge of a local cerebral maximum or local minimum, a predefined sequence of at least a local temporal maximum and at least a local temporal minimum of a cerebral slow wave or a rising or falling edge of such a succession.

19. Device according to any one of claims 1 to 18, wherein the support member (2) comprises an adjustment device (9) to the diameter of the head of a person for changing a dimension of said support member ( 2) according to a diameter of the head of a person.

20. Device according to any one of claims 1 to 19, wherein the adjustment device (9) of the support member (2) is a flexible and flexible portion of the support member (2), including a portion in fabric or elastomer.

21. Device according to any one of claims 1 to 20, wherein the adjustment device (9) of the support member (2) comprises at least two parts (9a, 9b), rigid or semi-rigid, movable. one with respect to the other.

22. Device according to any one of claims 1 to 21, wherein the support member (2) is adapted to surround at least a half of a circumference of the head of a person.

23. Device according to any one of claims 1 to 22, having a total weight of less than 200 grams.

24. A method for stimulating the slow brain waves of a person (P), in particular during a sleep period of said person, wherein the person wears a device (1) according to one of claims 1 to 18, the support element (2) of the device at least partially surrounding the head of said person so as to be maintained therein, the method comprising, in real time flexible:

the acquisition of at least one measurement signal (S) representative of a physiological electrical signal of the person by means of the plurality of electrodes (3) in contact with the skin of the person,

the reception of said measurement signal (S) by the onboard electronic conditioning and control electronics (5), and

the transmission by the acoustic transducer (4), on command of the on-board conditioning and control electronics (5), of an acoustic signal (A) synchronized with a predefined temporal pattern of slow cerebral wave (Ml) .

25. The method of claim 24, wherein, the emission of an acoustic signal (A) synchronized with a predefined temporal pattern of cerebral slow wave (Ml) comprises:

o the determination, from the measurement signal (S), of a cerebral slow waveform (F),

o determining, from said cerebral slow waveform (F), at least one timing instant of synchronization (I) between the predefined cerebral slow wave pattern (Ml) and a predefined temporal pattern of the acoustic signal (M2), and

o the control of the acoustic transducer (4) so that the predefined temporal pattern of the acoustic signal (M2) is emitted at said timing instant of synchronization (I).

26. The method according to claim 25, wherein the determination, from the measurement signal (S), of a cerebral slow waveform (F) comprises the servocontrol of an instantaneous phase of said temporal form ( F) on an instantaneous phase of the measurement signal (S).

The method of any of claims 25 and 26, wherein determining, from the measurement signal (S), a cerebral slow waveform (F) comprises:

determining a temporal shape (F) oscillating at a mean cerebral slow wave frequency of the person (P),

determining an instantaneous phase difference between said time form (F) and the measurement signal (S),

the slaving of an instantaneous phase of said temporal form (F) on an instantaneous phase of the measurement signal (S) as a function of said instantaneous phase difference.

The method of claim 27, wherein determining an instantaneous phase difference between said time form (F) and the measurement signal (S) comprises applying a low pass filter to a product between the time form (F) and the measurement signal (S).

The method of any one of claims 25 to 28, wherein the predefined cerebral slow wave time pattern (M1) has a predefined range of instantaneous phase values of the temporal shape (F) and / or a predefined range. amplitude absolute value of the measurement signal (S).

30. The method of claim 29, wherein the synchronization time instant (I) is determined as being a time instant during which the instantaneous phase of the time form (F) belongs to said predefined range of instant phase values of the time form (F) if and only if the absolute magnitude value of the measurement signal (S) has previously belonged to said predefined range of magnitude absolute value of the measurement signal ( S).

31. The method of claim 30, wherein

a first time instant is determined during which the absolute value of amplitude of the measurement signal (S) belongs to the predefined range of absolute value of amplitude of the measurement signal,

determining a second time instant, after the first time instant, during which the instantaneous phase of the time form (F) belongs to the predefined range of instantaneous phase value of the time form (F), and

if the first time instant and the second time instant are separated by a duration less than a predefined maximum duration, the synchronization time instant (I) is defined as the second time instant.

32. A method according to any one of claims 27 to 31, wherein, the average cerebral slow wave frequency of the person (P) is determined from a measurement signal acquired during a sleep period of said person preceding the sleep period during which the method is implemented.

33. Method according to any one of claims 27 to 31, wherein the average cerebral slow wave frequency of the person (P) is dynamically determined, in particular wherein dynamically determining the average cerebral slow wave frequency of the person from a portion of the measurement signal acquired over a predefined time period preceding the instant at which the determination operation of the average cerebral slow wave frequency of the person.

The method of any one of claims 25 to 32, wherein the predefined temporal pattern M2 of the acoustic signal comprises a predefined number of intermittent signals, in particular less than five intermittent signals.

35. Method according to any one of claims 24 to 34, wherein, the emission by the acoustic transducer (4), on command of the electronics (5) embedded conditioning and control, an acoustic signal ( A) synchronized with a predefined temporal pattern of cerebral slow wave (Ml) is reiterated at least once, especially at least once during a sleep period of the person (P).